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XP and the UV Meter by Bill and Sue Crain
Understanding UV Bill Crain
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Ultraviolet Light Spectrum
Xrays Heat and infrared Ultraviolet Light Spectrum The meter does not measure visible light. 280 290 300 310 320 330 340 350 360 370 380 390 400 Buckets represent wavelengths
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Even though the mask material is in front of all the suns rays, it blocks out only the UV rays. It lets all the visible light through so the kids can see colors! Window film or face mask material 280 280 290 290 300 300 310 310 320 320 330 330 340 340 350 350 360 360 370 370 380 380 390 390 400 400 No harmful UV can fill the buckets
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UV is like a swarm of insects,
some hurt more than others Filtered window or mask 2/24/2019 Bill Crain Ultraviolet Light Seminar “one father’s understanding”
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Window films let only the butterflies in
2/24/2019 Bill Crain
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Clear face shield filters UV light but allows visible
UVC UVB UVA Visible
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Clear face shield is equivalent to a UPF of >1000
DNA Damage in Skin
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UV Meter Reads UVA and UVB
UV Meter Range
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Behind mask, meter still measures non-zero
DNA Damage in Skin UV Meter Range
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Residual meter reading behind mask is okay
DNA Damage in Skin
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Window films Window films block 99.9% UV available for homes, buildings, and car Clear films available Darker tint does not necessarily mean better UV blocking Use a meter if film is unknown Other benefits of film include shatter resistance, energy savings, and tax benefits Some states prohibit windshield installation 2/24/2019 Bill Crain
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UV Transmitted Scattered Clouds 90% Snow Reflection 80% Broken Clouds
73% Shade 50% Overcast 33% Sand Reflection 25%
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Clothes Tightly woven fabrics are best
Denim is the best (UPF > 1000) Nylon is also excellent (UPF > 100) Wash clothes in RIT to add UPF Multiple layers helps Sunscreen + Proper Clothes = Healthy Skin 2/24/2019 Bill Crain
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Artificial Light Incandescent light bulbs < 60 Watts are okay from a distance of a few feet Halogen lights give off more UV than incandescents because they burn hotter and the glass bulb is less effective at blocking UV Fluorescents emit UVA and some UVB Solutions Use dimmer switches in the home Use fixtures that bounce light off ceiling or walls Cover fluorescents with UV filter sleeves or casings Increase your distance from the light source Generally, artificial light is 1% of the XP challenge 2/24/2019 Bill Crain
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In summary, how do we interpret a non-zero reading on our UV meters?
Know the UV source DNA damage depends on the UV spectrum The sun is 100 times more damaging than a fluorescent light bulb under typical conditions Know your protection Broadspectrum sunscreen (SPF plus UVA) Clothing has different levels of protection (UPF) Window film, sunglasses, shields Know your time DNA damage is cumulative Put minor or incidental exposures into perspective! 2/24/2019 Bill Crain
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The sun !! UV Concerns Not UV Concerns The moon and stars
Unfiltered windows Unfiltered fluorescent bulbs Halogen lights Unfiltered metal-halide lamps (rare to find unfiltered) Stadium lights with broken bulbs or fixtures Blacklight Headlights Some medical & dental lights Not UV Concerns The moon and stars Filtered windows Low wattage incandescent bulbs Filtered fluorescent bulbs Filtered metal-halide lamps Blacklight created from purple paint on incandescent bulbs Televisions, plasma screens, computers Camp fires LED lights 2/24/2019 Bill Crain
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Learning is experience. Everything else is just information
Learning is experience. Everything else is just information. – Albert Einstein 2/24/2019 Bill Crain
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Backup Slides 2/24/2019 Bill Crain
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2 times more sensitive to UVA than UVB Sensitive to some visible light
Should be recalibrated every few years 2/24/2019 Bill Crain Ultraviolet Light Seminar “one father’s understanding”
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Ultraviolet is divided into four bands
UV band Wavelength UVC 100 to 280 nm UVB 280 to 320 nm UVA 2 320 to 340 nm UVA 1 340 to 400 nm UVA1 does 1,000 times less direct DNA damage than UVB 2/24/2019 Bill Crain Ultraviolet Light Seminar “one father’s understanding”
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Ultraviolet Light Seminar
1 nm (nano-meter) = 10-9 m (meter) = meter = inch wavelength 2/24/2019 Bill Crain Ultraviolet Light Seminar “one father’s understanding”
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UVB small compared to UVA but does more harm
Visible Region UVA UVB SolarTech Model 5.7 Meter reading of 1000 uW/cm2 Alex Ryer International Light handbook UVB small compared to UVA but does more harm UVB level depends on ozone layer, latitude, and season No UVC gets through atmosphere UVC travels only a few feet in air – good news. 2/24/2019 Bill Crain Ultraviolet Light Seminar “one father’s understanding”
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UV measurements at a distance of 1-inch from bulb surface.
Light Source Manufacturer , Type Wattage UVA UVB UVA+B (Watts) uW/cm2 Incandescent GE softwhite 25 7 50 40 60 GE clear 98 2 100 175 5 180 GE reflector spot 150 243 250 Halogen GE floodlight 75 1185 15 1200 Westinghouse JDD Clear 1025 1100 Fluorescent Tube Phillips T12 tube 55 70 Compact Fluorescent Sunrise 23 383 42 425 2/24/2019 Bill Crain Ultraviolet Light Seminar “one father’s understanding”
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